Multiple Choice
In DNA replication, what is the direct substrate used by DNA polymerase to synthesize a new DNA strand?
8. DNA Replication
Overview of DNA Replication
Multiple Choice
In prokaryotic DNA replication, what is the primary function of DNA polymerase I?
A
Seal nicks between Okazaki fragments by forming phosphodiester bonds
B
Unwind the parental DNA double helix ahead of the replication fork
C
Synthesize the bulk of the leading and lagging strands with high processivity
D
Remove RNA primers with 5'→3' exonuclease activity and replace them with DNA nucleotides
Verified step by step guidance1
Understand the role of DNA polymerase I in prokaryotic DNA replication, which is distinct from other DNA polymerases like DNA polymerase III.
Recall that during replication, RNA primers are laid down to initiate DNA synthesis on both leading and lagging strands.
Recognize that DNA polymerase I has a 5'→3' exonuclease activity that allows it to remove these RNA primers from the newly synthesized DNA strands.
After removing the RNA primers, DNA polymerase I fills in the resulting gaps by synthesizing DNA nucleotides complementary to the template strand.
Note that other enzymes, such as DNA ligase, are responsible for sealing the nicks between Okazaki fragments, not DNA polymerase I.
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